Airsoft Ballistics recommends for those of you using bolt action sniper rifles that you never want to leave the spring compressed for long periods of time, as this will weaken the spring much faster and FPS will get lower.

When storing your bolt action sniper rifle it is best to remove the mag and fire the gun once or twice, this will verify that there are no BB's left in the hop up chamber and the spring will be left in the forward (non-compressed) position.